Pasi Virtanen

Aliquat 336®—a versatile and affordable cation source for an entirely new family of hydrophobic ionic liquids

A novel family of ionic liquids based on the tricaprylmethylammonium cation [C25H54N+] combined with a number of anions that are easily and elegantly prepared by means of simple replacement of the chloride, [Cl−], anion in Aliquat 336®—an ionic liquid itself—is introduced. Ionic liquids for engineering purposes should be affordable, easy to handle (i.e. air and moisture stable) and preferably simple to prepare by a non-expert in synthetic chemistry. Consequently, this paper introduces a viable option as a family of engineering-purpose ionic liquids derived from Aliquat 336®. Moreover, the prepared materials can be utilized, e.g. in heterogenized form as a catalyst incorporating catalytically active metal species (Pd) for the hydrogenation of an α,β-unsaturated aldehyde, citral.

Supported ionic liquids catalysts for fine chemicals : citral hydrogenation

The quest for new concepts in catalysis involving fine chemicals production is discussed. A new approach for easy preparation of structural, heterogeneous catalysts where the selectivity profile is altered by means of different ionic liquids and the same transition metal species (Pd) is introduced. Furthermore, an novel ionic liquid, [A336][PF6], derived from a common phase-transfer catalyst, Aliquat336®, was synthesized and utilized in catalytic hydrogenation of citral.

Switchable Ionic liquids (SILs) based on glycerol and acid gases

New types of switchable ionic liquids (SILs), containing 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), glycerol and an acid gas (CO2, SO2), were synthesized and characterized in this study. [DBU][Carbonate] or [sulfonate] were easily synthesized from a non-ionic mixture of molecular organic polyol and amidine base upon bubbling of an acid gas (CO2, SO2). Moreover, they were switched back to the original molecular solvents by flushing out the acid gas (CO2, SO2) by heating and/or bubbling an inert gas such as N2 through it. The structures of the SILs were confirmed by NMR and FTIR. The change from low polarity (molecular solvent) to high polarity (Switchable Ionic Liquid, SIL) was also indicated by the changes in properties, such as viscosity and miscibility with different organic solvents. The decomposition temperatures of the SILs were determined by means of Thermo Gravimetric Analysis (TGA) and gave values in the range of 50 °C and 120 °C for DBU-glycerol-CO2 (SIL1) and DBU-glycerol-SO2 (SIL2), respectively. Due to the reasonable decomposition temperatures, these novel SILs can be employed in multiple applications.

Switchable Ionic Liquids as Delignification Solvents for Lignocellulosic Materials

The transformation of lignocellulosic materials into potentially valuable resources is compromised by their complicated structure. Consequently, new economical and feasible conversion/fractionation techniques that render value-added products are intensely investigated. Herein an unorthodox and feasible fractionation method of birch chips (B. pendula) using a switchable ionic liquid (SIL) derived from an alkanol amine (monoethanol amine, MEA) and an organic super base (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) with two different trigger acid gases (CO2 and SO2 ) is studied. After SIL treatment, the dissolved fractions were selectively separated by a step-wise method using an antisolvent to induce precipitation. The SIL was recycled after concentration and evaporation of anti-solvent. The composition of undissolved wood after MEA-SO2 -SIL treatment resulted in 80 wt % cellulose, 10 wt % hemicelluloses, and 3 wt % lignin, whereas MEA-CO2 -SIL treatment resulted in 66 wt % cellulose, 12 wt % hemicelluloses and 11 wt % lignin. Thus, the MEA-SO2 -SIL proved more efficient than the MEA-CO2 -SIL, and a better solvent for lignin removal. All fractions were analyzed by gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), (13) C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC).

A morpholinium ionic liquid for cellulose dissolution.

A series of substituted morpholinium ionic salts and allyl ammonium acetates were prepared. Amongst those, N-allyl-N-methylmorpholinium acetate ([AMMorp][OAc]) was found to dissolve cellulose readily without any pre-processing of native cellulose. At 120°C, [AMMorp][OAc] could dissolve 30 wt%, 28 wt% and 25 wt% of cellulose with degree of polymerization (DPn) - 789, 1644 and 2082 respectively, in 20 min. Importantly, SEC analysis indicated that no discernible changes occurred in terms of the degree of polymerization of the different celluloses after regeneration. Furthermore, when comparing the cellulose dissolution capability of these newly synthesized ionic liquids, it is evident that the combination of all three constituents - the morpholinium cation, the existence of an allyl group and choosing the acetate anion are essential for efficient cellulose dissolution. The structure and morphology of the regenerated cellulosic materials were characterized by SEM, XRD, TGA, CP/MAS (13)C NMR and FTIR, respectively.

Treating birch wood with a switchable 1,8-diazabicyclo-[5.4.0]-undec-7-ene-glycerol carbonate ionic liquid

Abstract The suitability of a new switchable ionic liquid (SIL) has been investigated as a solvent for fractionation of lignocellulosic materials. SIL was prepared from inexpensive chemicals, e.g., glycerol, CO2, and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU). Fresh Nordic birch wood (B. pendula) was treated with the SIL for a time period of 1–5 days at 100°C and under atmospheric pressure. Upon SIL treatment, at best, 57% of the hemicelluloses were dissolved and 50% of lignins were dissolved from the native birch. The slightly fibrillated SIL treated chips contained about 55% cellulose. Up to 76% of the recovered species removed from the spent SIL liquor was originating from hemicelluloses, mainly from xylan. The spent SILs were reused for fresh wood dissolution in four consecutive cycles and each time the wood dissolution efficiency was similar. SILs could offer affordable (easy-to-synthesize) solvent systems for partial elimination of hemicelluloses and lignin from wood. SILs can also be prepared in-situ and on-site.

The Challenge of Efficient Synthesis of Biofuels from Lignocellulose for Future Renewable Transportation Fuels

Dehydration of sugars to 5-hydroxymethylfurfural (HMF) has recently been under intensive study by a multitude of research groups. On the other hand, when lignocellulosic biomass is applied as the starting material, very few studies can be found in the open literature. The direct synthesis of HMF, in line with the idea of “one-pot” synthesis strategy from lignocellulose, is demanding since the overall process should encompass dissolution, hydrolysis, and dehydration steps in a single processing unit. Ionic liquid-assisted methods to produce hydroxymethyl-furfural directly from lignocellulosic biomass are reported here together with a short overview of the most important biofuels. In reality, HMF is not suitable to be used as a single-component fuel as such, and, consequently, methods to produce HMF derivatives suitable as liquid fuels are reported.

Isomerisation of α-Pinene Oxide to Campholenic Aldehyde Over Supported Ionic Liquid Catalysts (SILCAs)

The isomerisation of α-pinene oxide to campholenic aldehyde, an expensive ingredient utilized by e.g. flavor industry, was studied over Supported Ionic Liquid Catalysts (SILCAs) consisting of catalytically active species residing in ionic liquid. The ionic liquid, in turn, was immobilized on a solid support material. SILCAs were demonstrated as efficient catalysts for the transformation of α-pinene oxide into campholenic aldehyde, with the product distribution and activity being dependent on the nature of the ionic liquid.

CHAPTER 1:The Biorefinery and Green Chemistry

If the living standards of western societies are to be maintained while those of the developing world change at their current tempo, then, because of the depletion of fossil resources and concerns about the environment, the concept of biorefining, following the principles of green chemistry as well as sustainability, will surely become more and more important in the future. This chapter introduces the concept of what biorefineries are and discusses their sustainability, taking into account green chemistry and engineering aspects. As well as a brief history, todays situation in the biorefining industry is covered with several examples. Also, the directions for the future biorefineries are considered.

The effect of switchable ionic liquid (SIL) treatment on the composition and crystallinity of birch chips (Betula pendula) using a novel alkanol amine-organic superbase-derived SIL

Abstract Two-step treatment of birch chips (Betula pendula) was tested using diethanolamine (DEA)-1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)-CO2-switchable ionic liquid (SIL), resulting in a 23% weight reduction in 24 h. The weight of the chips was reduced to 32% of their initial weight upon the second treatment with fresh SIL. SIL to wood ratio of 5:1, at 100°C for 24 h, without stirring, was applied in both steps. The relative amount of wood lignin reduced from 24% to 14% after two treatment cycles. The relative amount of cellulose of the undissolved fraction after SIL treatment increased from 43% (native birch wood) to 68% after the second cycle. Also, the undissolved material was efficiently fibrillated. The dissolved materials recovered from spent SIL, after treatment, contained high xylan content, about 90% of the total hemicelluloses, which was 85% of the recovered material. The powder X-ray diffraction (XRD) results revealed that the crystallinity of the undissolved material increased slightly, indicating dissolution of the amorphous material. Moreover, transformation of cellulose form I to form II in the remaining undissolved chips was not observed.